Logan Cox, the 3-year-old who was locked in a hot car in Lancaster last week, died Sunday morning at Carolinas Medical Center in Charlotte, officials said.

Lancaster County Coroner Mike Morris said he learned of Logan's death from the North Carolina Medical Examiner's Office in Charlotte.

At the time the N.C. officials called him, Morris said, they had not made a determination as to the cause of Logan's death. Medical examiners were waiting on information from the hospital to assist in their investigation.

Logan's family declined to comment on Sunday.

Logan suffered severe heat stroke on Wednesday after he climbed into a car with the family dog and became trapped inside at the family's home in the Buford community, the Lancaster County Sheriff's office said.

Jimmy Clevinger, Logan's grandfather, said last week that EMS took the boy, who was red-faced and complained of being hot, to the Buford Volunteer Fire Department, where he was flown to Carolinas Medical Center in Charlotte. On Thursday, Clevinger said Logan was not responding to stimuli like doctors wanted him to, but that they had been hopeful about his recovery.

Logan lived with his parents and grandparents. Deputies said it appeared Logan left his house without his mother’s knowledge. He was playing with one of the family’s dogs in the car, a black Mitsubishi Gallant, but could not get out.

Authorities were unsure how long Logan had been in the car. In a 911 call, Logan’s grandmother reported that her daughter had been asleep for about 30 minutes, and Logan, who she said figured out how to open the front door, had run out.

Logan and his mother, Amber Bender, had been sitting on the couch watching television when Bender “dozed off,” Clevinger said.

When she awoke, she realized her son was missing. Relatives found Logan in the car when they noticed the hazard lights blinking. Clevinger says the car doors were locked, but his grandson has learned how to unlock the car door. Clevinger believes Logan was unable to push the door back open because it’s heavy.

The family dog, a 9-year-old basset hound/pit bull mix, did not survive.